Variable width pulse generating system



Nov. 20, 1951 w. s. lvANs, JR 2,575,961

' VARIABLE WIDTH PULSE GENERTING SYSTEM Filed Oct. 5l. 1947 2 SHEETS-SHEET l CURRENT 600265 f 3nventor (Ittorneg Nov. 20, 1951 w. s. lvANs, JR

VARIABLE WIDTH PULSE GENERATING' SYSTEM Filed Oct. 51, 1947 2 SHEETS-SHEET 2 ra D/eefr fue E E' i. +T\/2/ eE/vr 4oz/ec;

11e/ease Plage-4 INE WV ENERTR FoLLon/EE AMPLIFIER Patented Nov. 20, 1951 `VARIABLE WIDTH PULSE GENERATING SYSTEM William S. Ivana, Jr., La Jolla, Calif., assigner to Consolidated Vultee Aircraft Corporation, San Diego, Calif., a corporation of Delaware Application October 31, 1947, Serial No. 783,390

21 Claims. V(Cl- Z50-27) The present invention relates to electrical pulse generating systems and more particularly to improved pulse generating systems which produce substantially rectangular pulses of electrical energy.

This invention contemplates the formation or generation of pulses by the utilization of a transmission line type pulse-forming network in conjunction with electronic space discharge devices and power supply and discharge timing devices. Pulse forming networks, or artiilcial transmission lines, as they are sometimes designated, have energy-storage and transmission delay characteristics which adapt them to the formation of accurate rectangular pulses. In the generation of pulses having high energy levels it is particularly desirable that the pulseforming network be discharged through a load by means of gas-filled electronic space discharge devices such as thyratron tubes since such tubes are capable of passing high currents with little power loss. An additional characteristic of the thyratron tube which renders it satisfactory for high level applications is the necessity of using but very little controlling energy to initiate the transition of the tube from a non-conducting state to the highly conducting state which is required by the pulse-forming operation.

Prior art methods of pulse formation have utilized pulse-forming networks in association with electronic space discharge devices and power supply and discharge synchronizing devices but such prior art methods have been restricted to those applications which require a relatively constant time width pulse output. This has been necessitated by reason of an operating characteristic of gas-lled electronic space discharge devices, such as thyratron tubes, and to the inflexibility of the transmission delay time characteristic of pulse-forming networks. The operating characteristic of a gas-filled electronic space discharge device which has this restrictive effect is the faculty that once such devices have been triggered from a non-conducting state to a conducting state, conduction will normally be maintained until the anode-cathode potential decreases to a very low value or is reversed in and the cessation of conduction therein is ordinarily equivalent to the time required for the charging or discharging ofthe pulse-forming network. In conventional applications this time interval is determined by the transmission delay time of the pulse-forming network in use. and represents the time required for the voltage and current wave, initiated at the instant the space discharge device is rendered conductive, to traverse the pulsefforming network, be reected by the eiiective 'open-circuit discontinuity at the end opposite to the load device, and to return to the starting point, thereby terminating thc period of conduction of the space discharge device, provided that the proper impedance relationship has been maintained between the load' device and the pulse-forming network. Since the transmission delay time of pulse-forming networks is not readily susceptible to variation, particularly if a constant network impedance is to be maintained, the time Width of the output pulse is essentially fixed. In the past, efforts to obtain variations in output pulse time width in pulse generating systems have been conned generally to mechanical switching between various sections of the pulse-forming network, or to short-circuiting of the load device a predetermined time after conduction has begun in the space discharge device. These expedients to effect variations are not particularly satisfactory. Mechanical switching devices ordinarily produce only discrete changes in output pulse width. are apt to be cumbersome, and are not adapted to the very rapid and continuous changes in pulse width demanded by pulse width modulation communication systems, this defect being due primarily to the mechanica-l inertia of the switch elements. The use of short-circuiting devices across the output load is likewise unreliable for such devices render the system susceptible to malfunctoning because of the production of transient disturbances during the short-circuiting operation.

It is therefore an object of the present invention to provide an improved form of pulsegenerating system for producing substantially rectangular pulses of electrical energy and wherein variations in pulse time width is eectively and readily obtained.

Another object of the invention resides in the provision of an improved pulse-forming system which affords continuous electronic control of output pulse time width between zero time width up to the maximum time width available from a given pulse-forming network (which latter time atraco:

3 width is ordinarily twice the trn d time of the network).

Another object of the invention lies in providing an improved pulse-generating system employing two load devices, connected to the opposite ends of the pulse-forming network, and wherein the total pulse timewidth characteristic of a given pulse-forming network can be divided in any desired ratio between the two load devices during the pulse-forming operation.

A further object of the invention is the provision of an improved pulse-forming system having continuous electronic control of the outputpulse time width and adapted for use in applications which require variations in load impedance, and which system permits desired variations without the appearance of objectionable reflected waveforms in the load output.

Other objects and features of the invention will be readily apparent to those skilled in the art from the following specification and appended drawings illustrating certain preferred embodiments of the invention in which:

Figure 1 is a schematic circuit diagram of a pulse-generating system embodying the principles of the invention; in this embodiment the invention utilizes a single output load and a resistive dummy load;

Figure 2 is a series of graphs which illustrate various time relationships involved in the pulse- `generating system of Figure 1;

drawings. Figure 1 is illustrative of one embodii ment of the invention. The pulse-generating system shown in Figure 1 comprises a usual pulse-forming network, indicated generally at l0, the discharge from which approximates a rectangular waveform and which is composed of a plurality of series inductances Il and shunt capacitors I2. One side of each of the capacitors l2 is connected to a common lead i3, with the opposite sides thereof being connected one -to the other, by the inductances l I. The number of inductances Il and capacitors I2 utilized is dependent uponthe degree of rectangularity. desired in the output pulse. In general, the greater the number of such components employed, the more nearly rectangular will be the output pulse waveform for a given pulse time width. The pulse-forming network I is the equivalent of a section of transmission line having a characteristic impedance \/1/c, wherein 1 is the effective inductance of one of the series inductances ll and c is the capacitance of one 0f the shunt capacitors i2, and which line has a one-way transmission delay time of V, where L represents the total eective inductance and C the total eective capacitance of the transmission line l0.

The pulse-forming network Iii is charged from 9, positive direct-current source, which may be a battery, with the energy being provided at a terminal I4 and passing therefrom through a seriesV charging inductance i5 and a series diode I6. During the period that this energy is stored the pulse-forming network lll.

by the pulse-forming network I l the network is largely capacitive in effect. with the combination of the charging inductance I6 and the aggregate of shunt capacitors I2 functioning as a series resonant circuit which charges the capacitors to a voltage considerably higher than the supply voltage, a value of 1.7 times the supply voltage having been found to be readily obtainable. This capacitor charging takes place in a half-cycle ofthe series resonant frequency because the unidirectional current fiowcharacteristic of the series diode i6 prevents the continuation of the charging oscillation. leaving the capacitors I2 charged to the highest attained positive voltage. The charge on the network capacitors l2 representa a store of electrical energy which may be released to provide short rectangular pulses of high peak power level. The value of the charging inductance i5 is required to be such that the charging half-cycle is completed between successive discharges of the line at the highest discharge repetition rate to be employed. During the brief pulse-generating operation, the relatively high inductance of this element I6 effectively isolates the power source from the pulse-forming network I0.

Connected tothe pulse-forming network I0 is a pulse transformer I1 having a primary i6, one side of which is connected, in series, to a high potential terminal i9 of the network and the other side to the anode 20 of a thyratron tube 2|, the cathode 2ia of which tube is connected to ground. The secondary 22 of transformer l1 is connected to a suitable load, which in the present instance, for illustrative purposes only, is a magnetron oscillator 23. 'I'he highpotential terminal 24 at the opposite end of pulse-forming network I0 is connected through a dummy resistance load 25 to the anode 29 of a thyratron tube 26, the cathode 26a of which tube is connected to ground. In this illustrative application both the magnetron load and the dummy load are made to have effective impedance equal to the characteristic impedance of The thyratron tubes 2| and 26 are characteristically normally non-conducting, and will remain so until triggered into a conducting state, independently of one another, by the application of positive pulses applied to their respective control grids.

The pairs of triggering pulses t1 and t2 required to eifect conduction of these tubes independently of one another are produced by a control circuit or timing system indicated generally at 28. The control circuit 26 comprises a pair of thyratron tubes 3| and 32, both of which are held in a normally non-conducting state by the impressing of negative voltages upon their control grids 33 and 34, with the negative voltagesbeing provided by a resistive network 35,` which is connected,k between ground and a negative voltage supply terminal 36. Connected between the anodes 31 and 33 of the tubes 3i and 32, respectively, and ground are capacitors 39 and 40 upon l which positive charges are stored, which charges are impressed through resistors 4| and 42 from a positive voltage source (not shown) which connects to terminal 43. A pair of resistors 44 and 45 connect the cathodes 46 and 41 of tubes 3l and 32, respectively, to ground, and a pair of lead lines 48 and 49 connect the same cathode's 46 and 41 to the control grids 5| and 52 of main thyratron tubes 26 and 2 l Raising the potential in a manner to be described, on the grids of control circuit thyratron tubes 3| and 32 momentarily to a level which will establish conduction in these tubes will cause condensers 39 and 40 to discharge rapidly through their respective associated tubes` and through the series cathode resistors 44 and 45. During this discharge, positive exponentially decaying pulse waveforms are produced at the cathode resistors 44 and 45, which are of an amplitude and duration suilicient to trigger the main thyratron tubes 26 and 2| into a conducting state. After discharge of the capacitors 39 and 40 current will cease to flow through the trigger-generating thyratron tubes 3| and 32 owing to the lack of a sufficient potential across the capacitors 39 and 40 to maintain a discharge, and these latter tubes revert to their normally non-conducting character. The capacitors 39 and 40 are slowly charged again through resistors 4| and 42 by the positive electrical energy provided at terminal 43 and then discharged during the succeeding pulse-forming operation in the manner described.

. Triggering of the thyratron tubes 3| and 32 to permit discharge of capacitors 39 and 40 is effected by the superimposing of a positivegoing timing or synchronizing waveform, having a sawtooth voltage-time characteristic, upon the negative bias voltages existing at the control grids 33 and 34 of these tubes 3| and 32. The timing waveform is supplied from a usual source Z which connects at terminal 53, and passes simultaneously through'blocking capacitors 54 and 55 and their associated isolating resistors 56 and 51 to the control grids 33 and 34 of thyratron tubes 3| and 32. The instant of conduction of each thyratron tube 3| and 32, and thus the instant of generation of each trigger pulse t1 and tz, is determined by the steepness of the timing waveform and by the amount of negative bias voltage applied to control grids 33 and 34 by the resistive network 35. The ele' ments comprising the source Z for the sawtooth timing waveform are shown in Figure 7. It is understood that the source Z herein described is but one form of sawtooth wave generating circuit that may be utilized with the present invention. The exact construction of this circuit forms no'part of the invention. As shown in Figure 7 this circuit comprises a blocking oscillator 200 composed of a transformer having a central windingy 202, to one end of which power is provided for the transformer from a positive direct current source B1. The other end of winding 202 is connected to lthe anode 203 of a triode vacuum tube 204, the cathode 205 of which tube is connected to ground. A second Winding 206 of the transformer 20| has one end connected to ground and the opposite end connected through a capacitor 20611 to the control grid 201 of the tube 204; a resistance 200 is also connected to this control grid 201 and to ground. A sine wave generator 209 provides a source of modulating current and is connected to the control grid 201. Any device or source providing a modulating waveform may be employed. The blocking oscillator 200 is connected to a cathode follower amplifier 2||, the connection thereto being made by joining one end of a third winding 2|0 of transformer 20| to the control grid 2|2 of a triode vacuum tube 2| 3 included in amplifier 2||. The opposite end of winding 2|0 is connected to a direct current voltage source Bz which provides the negative bias voltage for the control grid 2|2 of tube 2|3. The anode 2|4 of tube 2|3 is connected to the positive direct current source Bi. The cathode 2|5 of tube 2|3 is connected to ground through a resistance 2|6. A capacitor 2|1 connects to cathode 2|5 and to ground. A lead 2|8 interconnects the cathode 2|5 and the terminal 53 at which the timing waveform for control circuit 28 is introduced.

The time phasing of the trigger pulses can be controlled by variation of the relative bias voltages applied to the thyratron tubes 3| and 32. In the present embodiment, for sake of illustration a fixed bias voltage has 'been provided at the control grid 34 of thyratron tube 32 and a variable bias voltage has been provided at the control grid 33 of thyratron tube 3|. Resistor 58 interconnects resistive network 35 and isolating resistor 51 associated with control grid 34 of thyratron tube 32 whereby a fixed bias voltage is applied to this control grid. To effect variation of the bias voltage at control grid 33 there is provided a potentiometer 62 interconnected between the negative voltage supply terminal 36 and ground, with the potentiometer 62 having a variable arm 62a. Resistor 6| interconnects variable arm 62a and isolating resistor 56 associated with control grid 33 of thyratron tube 3| whereby a variable bias voltage is applied to this control grid. Adjustment of the variable arm 62a to desired positions results in a fixed pulse width output at the magnetron oscillator 23 for each setting of the variable arm.

As shown, the variable arm 62a of potentiometer 62 isconnected through a blocking capacitor 63 to a terminal 64, at which terminal a modulating Waveform may be applied. As here shown a usual sine wave generator 60 provides the modulating waveform; any usual modulating wave source may be utilized. Through this means the bias voltage at the control grid 33 of thyratron tube 3| may be varied, with the pulse width output at the magnetron oscillator 23, in this case, varying in accordance with the variations in the modulating waveforms that may be supplied. Thus two methods of varying the pulse width output of the embodiment of Figure l are provided, one by movement of the adjustable arm 62a of the potentiometer 62, and the other by supplying a varying modulating waveform to the arm 62a.

Pulse formation in the embodiment of Figure 1 occurs when the pulse-forming network I0 discharges, with ythe pulse-forming network l0 discharging when the main thyratron tubes 2| and 26 controlling it are triggered into a conductive state by pulses provided by the tubes 3| and 32.

Triggering of thyrotron tube 26 into conduction connects dummy resistance load 25 into the pulse-forming network |0 and a voltage and current wave is formed which transverses network |0, traveling toward thyratron tube 2| connected to the opposite end thereof. Upon arrival of this wave at tube 2| the conductive state of the latter is terminated, because of a reduction to zero of the anode-cathode potential, to terminate the output pulse appearing at the magnetron oscillator 23. Similarly. arrival of the voltage and current wave initiated by the conduction of thyratron tube 2| terminates conduction of thyratron tube 26, leaving the pulse forming network completely discharged.

The pulse-forming network will again be charged from current supplied by the Idirectcurrent source at terminal |4 and passing therefrom through the charging inductance I5 and the series diode Il. andwill bs dischargedonce more when a pair of trigger impulsesare pro' pulses has been described. The circuit 2l, as has been stated, is understood to be illustrative of but one form of timing circuit adapted to be manually adjusted to provide any desired fixed output pulse width from zero up to the maximum time width which the network l is capable of producing, or which may be 'made to produce any desired variation in the width of successive output pulses within these limits. as in accordance with the characteristics of ai modulating waveform.

Practical application of the invention has been had and a construction in accordance with Figure 1 has been assembled and tested. A ten section pulse-forming network I0 was devised having a one-way transmission delay time of l microsecond and a characteristic impedance of 50 ohms, which network was charged from a positive 4000 volt direct-current source, through a charging inductance i5, having a value of 2.75 henrys, and a type 3B24 series diode i6. A 50 ohm resistance, substantially non-inductive, was utilized as the dummy load 25. A pulse transformer I1 having a 4.5 to 1 turns ratio was employed with connection being made to a type 725A magnetron oscillator 23. The main space discharge tubes 2| and 26 were hydrogen thyratrons of the r4G35 type, and the trigger generating tubes 3| and 32 were miniature thyratrons of the 2D2gl type. With this combination of elements, continuously controllable division of the `network pulse output between the magnetron oscillator 23 load and the dummy load 25 was obtained. The precision of triggering obtained was such that the variation or jitter in output pulse width and time position was negligible, estimated at being less than 0.02 microsecond.

Figure 2 depicts curves which are illustrative of the time values involved in the operation of the embodiment of Figure l; the time relationships between the timing waveform which initiates trigger formation at thyratron tubes 3| and 32, the trigger pulses tz and t1, the pulses generated at the magnetron oscillator 23 output load and at the dummy load 25 for a particular setting of the control grid 33 bias level at thyratron tube 3|, are represented, respectively, by

v curves A, B, C, D and E. The setting of the bias level of control grid 33 of tube 3| is for purpose of illustration made more negative than the level at the control grid 34 of tube 32, so that trigger formation at the latter tube occurs before trigger formation at tube 3|. The output pulse time width at the magnetron oscillator 23 is equal to Tu-(t2-t1), where To represents the one-way transmission delay time of the pulse-forming network and t2 and tl are the time instants of effecting conduction of thyratron tubes 2| and 26 respectively. The interval (t2-t1) can be varied between the limits of vplus To and minus To to produce full variation in the pulse width appearing at the magnetron load 23, from zero width to twice To, which is the maximum width obtainable.

It is noted that the relative voltage amplitudes illustrated in Figure 2 .have been exaggerated for a more ready understanding of the invention. In practice, the output waveforms appearing at the magnetron oscillator 23 and the dummy resistance load 2l may have nany times the amplitude of the timing waveform and trigger pulses, and the actual magnetron oscillator terminal voltage drop is greater than the dummy load voltage drop, owing to the effect of transformer il. All waveforms shown are idealized, inasmuch as perfectly sharp leading and trailing edges are not obtainable in practice.

The circuit illustrated in Figure l is satisfactory for use particularly in those applications in which the pulsev power dissipated by the dummy load 26 is of no consequence. During each pulse-forming discharge of the network III the energy stored in the network capacitors I2 is almost completely dissipated, this being a consequence of providing a magnetron load 23 and a dummy load 25 which have effective impedances equal to the characteristic impedance of the-network I0. During discharge the voltage of each traveling wave has an amplitude approximately one-half that of the network storage potential and the traversing of the network by these waves almost completely exhaust the stored energy. In some applications this is an advantage in that the recharging cycle produces the same network storage energy after each discharge regardless of the manner of division of pulse .width output. 'I'here are, however, applications in which it is expedient to reduce the impedance of the dummy load to a condition approaching short-circuit, in order to reduce the dissipated power. Figure 3, which will be described in detail hereinafter, is illustrative of a circuit embodying this variation.

The present invention contemplates the use of either a pair of useful load devices, or of one useful load device and a dummy load device, as has just been described in connection with Figure l. with one device connected at each end of a pulse-forming network, and with'the connection between the load devices and the energystoring network being controlled by electronic space discharge devices, such as thyratron tubes. As is weil known, thyratron tubes are normally non-conducting and are triggered into a conducting state by the application thereto of` relatively low energy triggering pulses. The/triggering pulses required for use in the present invention are provided in spaced pairs. The particular .mechanism and devices for producing the triggering pulses form no part of this invention; any usual means for so doing may be employed, and it is understood that the method hereinbefore described is to be taken as merely illustrative. The period between pairs of triggering pulses represents the period between pulse generation by the pulse-forming system. The time phasing relationship which exists between the individual triggering pulses which constitute a pair determines the manner of division of the total time width characteristic of the pulseforming network between the two load devices. In the instance where a single useful load device and a dummy load are utilized, the time plfasing of the trigger pulses determines the time width of the output pulse appearing at the single useful load. The dummy load here may be of either a dissipative or non-dissipative character, or it may be a device for returning energy to the primary supply source, or further, under some circumstances, it may be a short circuit. However, in each case the principle of pulse time width variation is the same. For in the present invention as a dummy load device is connected to its appropriate end of the pulse-forming netaumen work. through the triggering of its associated space discharge device into conduction, a voltage and current wave is formed which traverses the pulse-forming network traveling toward the opposite load device and space discharge device. The arrival of this wave at the opposite end of the pulse-forming network terminates the conductive state of the electronic space discharge device there present by its either reducing the anode-cathode potential of this space discharge device to a value too low to sustain conduction or by reversing the polarity of the anode-cathode potential, and thereby terminates the output pulse appearing at the load.

If two useful load devices are contemplated in association with a pulse-forming network, with these load devices having an impedance equal to the characteristic impedance of the network, a complete charge or discharge of the pulse-forming network will take place in a period varying from an amount equal to the one-way transmission delay time of the network to an amount twice such network delay time, dependent upon the manner of division of the total pulse output width between the two load devices. The

of pulse-forming system, are capable, normally, of conduction in only one direction. The output pulse time width at the single useful load is therefore to be indicated by the expression To+(t2-t1), with tz and t1 representing respectively the time of triggering of the dummy load and the output load device.

The above discussed electrical charge of opposite polarity appearing at 'the output load space discharge device terminates conduction therein, as has been stated, but tends to persist after the pulse-forming operation has been accomplished. This charge represents a storage of energy in the pulse-forming network. This energy may be time width of the pulse appearing at the output loads may be indicated by the expressions other, where To represents the one-way transmission delay time of the pulse-forming network, t1 represents the time of triggering of the space discharge device which connects a load device at `one end of the pulse-forming network', and tz is the time of triggering of the space discharge device which connects a dummy load or a load device at the opposite end of the network. The time interval (tz-t1) is controlled by the generating system which provides the pair of triggering impulses for operation of the two space discharge devices connected to the ends of the pulseforming network. Variation of the time interval (t2-eti) between the limits of plus and minus To represents the complete variation of pulse output division between the two loads. With a condition of tz=t1 both trigger pulses are applied simultaneously, and the output pulse at each load will have a time width To.

Where but a single useful load device is to be utilized, having an impedance which may be varied over awide range, it is expedient to use a dummy load having an impedance either equal to orv lower than the characteristic impedance of the pulse-forming network in order that the output load waveform will be free of the undesirable reilected waveforms which ordinarily follow the principal pulse waveform in applications where the effective output load impedance is higher than the impedance of the pulse-forming network. The use of a dummy load of the character above specified provides for the formation of a voltage and current wave of such magnitude that the cessation of conduction of the space discharge device associated with the output load device is assured despite wide variations in impedance.

A dummy load having an impedance lower than the network impedance provides a current and voltage wave which on arrival at the opposite end will-cause a reversal of polarity of the voltage appearing across the output load space discharge device located there. This will effectively terminate conduction in such space discharge device, since inherently electronic space discharge devices such as thyratron tubes, which are ordinarily utilized and are best suited for this type removed through the use of a clipping diode, or it can be effectively reversed in polarity through the use of a diode and series inductance to provide a part of the energy required for the formation of the succeeding pulse or pulses, as will be hereinafter more fully described and explained.

The various embodiments of the present invention will all make use of traveling voltage and current waves which originate from opposite ends of a section of electrical transmission line or equivalent pulse-forming network. These traveling waves are initiated by rendering conductive the pair of normally non-conducting electronic space discharge devices provided at each end of the pulse-forming network. It is here again noted that the time relationship between the beginning of.conduction of each of these space discharge devices determines the time width of the output pulses which will be produced at the two independent load devices. The arrival of a traveling wave originating at one end at the opposite end of a pulse-forming network results in a cessation of conduction of the space discharge device connected to the load at such opposite end and a consequent cessation of the pulse output appearing at such load, provided that the proper impedance relationships have been maintained.

The pairs of triggering pulses which render the space discharge devices conductive can be generated by any of the usual methods well known to the art, and vthe relative time phase relationship between the trigger pulses which constitute a pair can be rapidly and continuously varied,

producing a correspondingly rapid and continuous change in the time width of successive pulses produced at the load device or devices. Pulse formation in accordance with this invention can be accomplished through either charging or discharging of a pulse-forming network, or by alternate charging and discharging of the network, as will be hereinafter described. Any one of a variety of load devices may be expeditiously employed in the present invention, for example: resistance loads, magnetron oscillators, laboratory pulse generators and other similar apparatus useful in applications wherein there is desired to employ accurate, rapidly repeated signals of short duration. The arrangement of components can be varied to accord with the requirements of particular operational situations without departing from the spirit and scope of this invention. Electronic space discharge devices of the gasI filled Ithyratron type, being eiiicient and easily controlled, are particularly well suited to this method of pulse formation, as has been discussed; however, other types of space discharge devices can be used, such as high-vacuum discharge devices or spark discharge devices. The electrical power source utilized to charge the pulse-forming network for the production of pulses may be either alternating or direct current.

The embodiment of Figure 3 is an illustration of a circuit wherein the impedance of the dummy load is reduced to a. condition approaching short circuit in order to reduce dissipated power. 'I'his embodiment comprises a pulse-forming network, Yindicated generally at 10, which provides a .discharge of approximately rectangular waveform, and which is composed of a plurality of shunt capacitors 1|, each of which has one side connected to `a common lead 12, and the opposite sides connected one to the other by inductances 18. As with the pulse-network I0, the number of condensers 1| and inductanees 18 utilized by pulse-network 18 is dependent on the degree of rectangularity .desired in the output pulse. Network 18 is provided with electrical energy at terminal 14, from an alternating current high voltage source, not shown, with the charge passing from terminal 14 through a charging inductance 18. 'Ihe storage of a charge on pulse-forming network 1|| is accomplished in fundamentally the same manner as in the case of the pulse-forming network I8 of the embodiment of Figure 1. However, a restriction on the operation of network 18 arises due to the omission of a series charging diode similar to diode I6 of Figure 1. This restriction is placed upon the repetition rate and time phase position of the pulse-forming action. for this action must occur innetwork 10 during a positive portion of the line potential storage waveform, which follows the alternations in voltage of the alternating current 'power source which charges network 10. However in many applications, such as in some radar systems, this restriction is not a serious one, as the output pulse repetition rate may protably be synchronous with the power supply frequency.

The point of connection of the charging inductance 18 to the pulse-forming network 18 is not Acritical for the charging eiilciency will be substantially the same whatever the point of connection, and during the pulse-forming operations the relatively high inductance of .device eectively isolates the power source from network 18.

A- pair oi thyratron tubes 16 and 11 are connected to opposite ends of the pulse-forming network 18, with the connection being made to the anodes 18 and 19 of these tubes. Variable load resistances 8| and 82 are provided, one associated with each tube 16 and 11, which variable load resistances are connected between cathodes 83 and 84 of tubes 18' and 11, respectively, and ground. A pair of pulse transformers 85 and 86 are connected, respectively. to control grid 81 of tube 18 and control grid 88 oi.' tube 11, and provide negative bias voltages on such grids whereby the vthyratron tubes 16 and 11 are held in normally non-conducting state. Pairs of trigger pulses t1 and t2 are generated by external timing circuits, not shown to avoid repetition, but which may be of the type utilized by the embodiment oi.' Figure 1 and indicated generally at 28, and which is associated with the source Z which provides a sawtooth wave. Any other similar circuit may of course be utilized. These trigger pulses ti and tz are applied to the control grids 81 and 88 oi' tubes 16 and 11 through terminals 8| and 92 of the pulse transformers 85 and 88. Again as in the case of the embodiment of Figure l the time phasing of the trigger pulse pairs determines the time division of the pulse forming network output, which in the present embodiment is to be divided between the load resistances 8| and 82. Terminals 88 and 94 are provided, respec- .ing the desired rectangular characteristic.

l2 tively, at load resistances 8| and 82 at which the output of network 10 will appear to be carried to the point of utilization.

To illustrate a useful characteristic of the pulse-forming system of Figure 3, it will be assumed that the load resistance 82 has an impedance several times the magnitude of the characteristic impedance \/1/c of the pulse forming network 10. In the conventional method of forming pulses, a pulse output characteristic similar to curve F shown in Figure 4 would be obtained at output terminal 84. 'Ihis condition could be obtained in the system of Figure 3 by deliberately omitting trigger pulses t1; so that tube 16 and its associated load resistance 8| would be effectively isolated from the network 18. An output waveform of this character is undesirable in applications which require rectangular pulse output; therefore, in the conventional pulse-forming systems, the load impedance must be restricted to magnitudes equal to or lower than the magnitude of the characteristic impedance of the pulse-forming network. In the system of Figure 3, to obtain a rectangular pulse at output terminal 94 the load impedance is not subject to this restriction, because of the utilization of the load resistance 8| and its associated tube 16. Load resistance 8| is set to an impedance value equal to or less than the characteristic impedance of the network 1|) and by triggering the two thyratron tubes 16 and 11 by means 0i' paired trigger pulses the rectangular characteristic of the pulse output at output termina] 94 can be maintained despite a wide range of impedance mismatch, and the load output 82 may have either a higher or lower impedance than the characteristic impedance of the network 10. The traveling voltage and current wave provided when load resistance 18 is utilized in the system, which wave traverses the pulse-forming network to' act upon the thyratron tube 11 at the opposite end, is the effective factor in secur- A pulse waveform of the type that will appear at Output terminal 94 in the present embodiment of the invention is illustrated by curve G of Figure 4. It is here noted that the pulse waveform is free of undesirable reflections, and that the pulse width is variable between zero and 2To.

'A negative charge may be left on the capacitors 1| of pulse-forming network 18 in the operation thereof. This negative charge will ordinarily be reversed during the succeeding network charging cycle, after the thyratron tubes 16 and 11 have recovered to their normal non-conducting state wherein they are again adapted to be used to provide energy for succeeding pulse formations. In particular applications, the load resistance 8| may be4 replaced by a. direct connection to ground, in which case the thyratron tube 16 is used only for the control of the output pulse width and for the provision of a greater impedance flexibility at output terminal 94.

The load impedance flexibility obtainable by the use of the present invention is particularly useful in such applications as pulse modulation of magnetrons, where the magnetron impedance ordinarily rises as theapplied pulse voltage is lowered below the optimum value; or in use with laboratory pulse generators, where a wide range of output impedance values is desirable.

Figure 5 illustrates another embodiment of the invention wherein variable-width pulse formation is accomplished during both the charge and the discharge of a pulse-forming network.

13 As shown this embodiment comprises a pulseforming network |00, similar in operation and construction to pulse-forming networks and hereinbefore described. Network |00 is composed of a plurality of interconnected shunt capacitors |0| and series inductances |02. A pair impedances and the pulse transformer ratios be so chosen that each load device presents an impedance in series with the pulse-forming network |00 equal to the characteristic impedance of the network during charging and discharging operations. A thyratron tube Hly is connected torone end oi? the winding 05 of transformer |03 and a second thyratron tube H2 is connected to the opposite side thereof, the connections being made through the cathode H3 of tube and anode l!! of tube H2. Two thyratron tubes ||5 and H6 are similarly connected to opposite ends of winding |06 of transformer |04, through cathode ||1 of tube H5 and anode H8 of tube H6. The windings |05 and 01 of pulse-transformer |03 and windings |08 and |08 of pulse-transformer |04 are so arranged that current ilow into the pulse-forming network |00 during the charging operation and current now out of the network during the discharging operation produces pulses of the same polarity at the load devices to be associated with this system. Thyratron tubes Iand H5 are effective in producing pulse formations during the charging of the pulseforming network |00 and the oppositely disposed thyratron tubes H2 and ||6 are effective in producing pulse formation during the discharging of the network |00.

Power for effecting operation of this pulsegenerating system is provided by a high voltage direct current source with a positive polarity connection being made at terminal |2I. A capacitor |22 is connected between terminal |2| and ground, which capacitor acts to reduce the effective impedance of the power supply during the network charging operation.

Pairs of trigger pulses t1 and t2 for operating thyratron tubes and H5 are supplied at terminals |23 and |24 from a trigger generating circuit, or source, not shown and which again may be of the type utllizedby the embodiment of Figure 1; which pulses pass through isolating pulse transformers |25 and |26 associated with these tubes and H5. The pulse transformer |25 associated with tube has a winding |21 connected to ground and a winding |28 connected between the control grid |3| of the tube and the winding |05 of pulse transformer |03. The pulse transformer |26 associated with tube H5 has one winding |32 which is connected toground and a second winding |33 interconnecting the control grid |34 of tube H5 and winding |06 of pulse transformer |04.

A similar arrangement for eiecting operation of the thyratron tubes ||2 and H8 is provided. 'I'he pairs of triggervpulses t1 and t2 for effecting operation of these tubes ||2 and I6 are supplied by a trigger generating circuit, not shown, which is connected to terminals and |36. An isolating pulse transformer |31 is connected between terminal |35 and thyratron tube ||2 and 14 a second isolating pulse transformer |38 is provided between terminal |38 and thyratron tube 6. The pulse transformer |31 has a ilrst windling |4| connected between terminal. |35 and ground and a second winding |42 connected between the control grid |43 of tube H2 and ground. The pulse transformer |38 is provided with a winding |44 connected between terminal |36' and ground, and a winding |45 connected between the control grid |46 of tube H6 and ground.

The rate at which the external generating circuits, which is understood to be of the type utilized by the embodiment of Figure 1 employed by the present embodiment provides the pairs of trigger pulses for operating the various thyratron tubes of the present embodiment determines the repetition rate at which charge and discharge of the pulse-forming network |00 occurs. The phasing of the trigger pulses which constitute a pair determines the manner of division of the pulse output of network |00 to the load devices connected to pulse-transformer |03 and pulsetransformer |04. It is understood that the phasing may be accomplished in any well-known manner, the method described in connection with the embodiment of Figure 1, it is contemplated, may here be employed.

The circuit of Figure 5 operates in the same fashion during both the charging and discharging stages to produce variable width pulses. In each instance the space discharge devices provided at each end of the network' |00 are triggered into conduction to effect a flow of current and to initiate current and voltage waves which travel from one end toward the opposite end of the network and upon arrival there eiect a cessation in conduction of the space discharge device there located and consequently cause cessation of the pulse output in the load connected thereto. A high pulse repetition rate is obtainable with this embodiment of the inventicnsince charging and discharging of the network is accomplished very rapidly.

As has been stated the thyratron tubes I I and ||5 produce pulse formations during charging of network |00 and the thyratron tubes H2 and H6 are operative during discharge of network |00.

Assuming that zero potential exists on pulseforming network |00, triggering of tubes and H5 into conduction by a pair of trigger pulses results in the initiation of pulse output at both of the load devices at pulse-transformers |03 and 04. Traveling voltage and current waves are formed in network |00 having voltage amplitudes approximately equal to one-half the supply voltage amplitude. The arrival of the respective traveling waves at the opposite ends of network |00 halts conduction of the tubes H| and H5 and terminates the pulse output appearing at each load device and leaves the network |00 charged to approximately the full sunply voltage. The next operation involves the discharge of network |00 when thyratron tubes H2 and H6 are triggered into conduction by a pair of trigger pulses supplied at terminals |35 and |36 and through isolating pulse transformers |31 and |38. Again the pulse output at each load device associated with pulse-transformers |03 and |04 is initiated at the moment of conduction of the associated thyratron tube and is terminated by the arrival of the voltage and current traveling wave initiated at the moment of conduction of the thyratron tube connected at the opposite end of the network. As during the charging operation. the phasing of the trigger pulses which constitute a pair determines the manner of division of pulse-forming network out- Dut between the two load devices. `The time width of the pulse output appearing at the load device at pulse-transformer |03 is given by the expression To-i- (t2-t1) and the time width of the pulse output at the load device at pulse-transformer |04 is given by the expression To-(ta-ti) with To representing the lone-way transmission delay time of the pulse-forming network and t1 and t2 representing the time of triggering into conduction of thyratron tubes and 5, or alternatively, tubes ||2 and ||6.

Figure 6V illustrates an embodiment of the invention whichl provides for the formation of pulses during the rapid charging of a pulseforming network from a source of electrical energy, with the charge formed on the network capacitance being either dissipated or reversed in polarity during the time period between pulse formation.

As in the other embodiments a pulse-forming network equivalent to a section. of electrical transmission line is employed, herein indicated generally at |50. This network |50 is also comprised of a plurality of shunt capacitors |5|. joined by a common lead line |52, at one of their sides, and interconnected at their other sides by a plurality.of series inductances |53. High voltage from a direct current source is provided for, the pulse-forming network |50 at a terminal |54. A capacitor |55 is connected between the high voltage terminal |54 and ground, and is provided to effectively decrease the impedance of the high voltage source during the pulse-generating operation, which will ordinarily require a verv high momentary current flow from the current source, most of this momentary current being supplied from the charge accumulated on capacitor |55.

A series diode |56 and series inductance |51 are connected between the terminal |58 of network |50 and the high voltage terminal |54.

A pair of output pulse transformers |6| and |62 is connected to the network |50, one at each end thereof. Also connected to the opposite ends of the network |50, by the transformers 6| and |62, are thyratron tubes |63 and |64. Pulse transformer |6| is provided with a winding |65 which is connected to ground and a winding |66 which interconnects anode |61 oi' tube |63 and the network |50: and pulse transformer |62 has a winding |68 'which connects to ground and a second winding |69 which connects anode |1| of tube |64 to network |50.

The load devices to be employed with this embodiment of the invention are connected thereto by the windings |65 of pulse-transformer |6| and |60 of pulse-transformer |62.

The thyratron tubes |63 and |64 utilized are of the usual normally non-conducting type, and have their cathodes |12 and |13 connected to 'Ihe present embodiment of the invention will operate as follows, assuming first an absence of charge on the capacitors |5| of pulse-forming network on triggering of the thyratron tubes |63 and |64 into conduction there results a flow of current through pulse transformers |6| and |62 and there will be initiated a pulse output at the load devices associated with the pulse transformers |6| and |62. Traveling voltage and current waves are initiated by the iiow of current at the two ends of the network |50, which waves traverse the network in a time equal to the transmission delay time of the pulse-forming network. Conduction oi' each thyratron tube |63 and |64 and pulse output at the load devices controlled by these tubes is terminated by the arrival of the traveling wave from the opposite end of the network |50, thus with the cessation of conduction of both thyratrons the pulse-generating operation is completed. 'I'he pulse-forming network |50 is left in a charged condition immediately following the pulse-generating operation. The magnitude and: polarity of this charge is such as to prevent conduction in either thyratron. This charge is reversed in polarity before the next pulse-generating operation; reversal is accomplished through the use of the .series diode |56 and the series inductance |51 connected to the network |50. The combination of the inductance |51 and the aggregate of the line capacitors |5| results in a half-cycle of oscillatory discharge through the series diode |56. which permits current flow in one direction only. This action effectively revrss the polarity of the charge on the network capacitors |5|. The net effect is to provide an increased supply voltage for the formation of the succeeding pulses. The value `oi.' the series inductance |51 is so chosen that the reversal half-cycle takes place within the time period between the generation of successive pulses. A restriction upon the minimum time of reversal is imposed bv the deionization time of the thyratron tubes. The relatively high reactance of the series inductance |51 effectively isolates it from the pulse-forming network during the brief interval of pulse-generation. The duration of the conduction interval nf each thryatron tube. and the conseouent time duration of the rectangular pulse output in the as- 5 sociated load devices. is determined bv the transground. The tubesl |63 and |64 are rendered 65 mission delay time of the pulse-forming` network |50 and upon the relative time phasing of the triggering into conduction of the thyratron tubes. It is understood that. as in the other embodiments of the invention. the time phase of the triggering pulses can be adjusted either manually or in accordance with a modulating waveform to provide for continuously variable division of the pulse width characteristic of the pulse-forming network between the two load devines employed.

An advantage common to the various embodiments of the invention. which is realized when both of the load devices have eoual impedance. .is the fact that for a given pulse repetition rate, the load offered by the pulse-forming network to the primary power supply is constant, regardless of the manner in which the pulse output is divided. This permits pulse-width adiustment or modulation without an attendant change in pulse amplitude. since the voltage regulation of thel power supply does not become a factor in determining output pulse amplitude unless the repetition rate is changed.

While certain preferred embodiments of the y invention have been specifically disclosed, itis understood that lthe invention is not limited thereto as many'variations will be readily appar-,-

ent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims. I

Iclaim: 1. In a pulse generating circuit, a pulse-formling network wherein electrical energy is adapted to be stored, said network having va connection to a source of electric current supply load devices connected to said network and at each end thereof. means for intermittently electrically interconnecting' said load devices with said network comprising a normally non-conducting electronic space discharge device operatively associated with.

each of said load devices and having a series connection therewith and a connection to ground and means operatively connected to said electronic space discharge devices for rendering said space discharge devices conductive to thereby initiate pulse generation.

2. In a pulse generating circuit, a pulse-forming network wherein electrical energy is adapted to be stored, said network having a connection to a source of electric current supply load dcvices, each having an impedance equal to the characteristic impedance of the network, connected to said network and at each end thereof, a normally non-conducting electronic space discharge device operatively associated with each of said load devices and having a series connection therewith and a connection to ground, and means operatively connected to said electronic space discharge devices rendering said space discharge device conductive, and independently of one another, to thereby initiate pulse generation.

' 3. In a pulse generating circuit, a. pulse-forming network wherein electrical energy is adapted to be stored, said network having a connection to a source of electric current supply load devices connected to said network and at each end thereof, a normally non-conducting electronic space discharge device operatively associated with each of said load devices and having a series connection therewith and a. connection to ground, and means operatively connected to said electronic space discharge devices for rendering said space discharge devices conductive, and independently of one another, to thereby initiate pulse generation. said means for rendering said space discharge devices conductive comprising means operative to eiect division of the maximum pulse time width characteristic of the pulseforming network in a predetermined ratio between said load devices.

4. In a pulse generating circuit, a pulse-forming network wherein electrical energy is adapted to be stored, said network having a connection to a source of electric current supply load devices connected to said network and at each end thereof, a normally non-conducting electronic space discharge device operatively associated with each of said load devices and having a series connection therewith and a connection to ground, and means operatively connected to said electronic space discharge devices for rendering l said space discharge devices conductive, and'in-l dependently of one-another, to thereby initiate pulse generation, said means for rendering said space discharge devices conductive comprising means to establish the length of the time interval between successive pulse-generating operations.

5. In a pulse generating circuit, a pulse-forming network wherein electrical energy is adapted to be stored,7 said network having a connection to a source o! electric current supply load devices connected to said network and at each end thereof, a normally non-conducting electronic space discharge device operatively associated with each of said load devices and having a series connection therewith and a connection to ground, and means operatively connected to said electronic space discharge devices for rendering said space discharge devices conductive, and independently of one another, to thereby initiate pulse lgeneration,'said means for rendering said space discharge devices conductive comprising means operative to etlect division or the maximum pulse time width characteristic of the pulseforming network in a predetermined ratio between said load devices, and means to establish the length of the time interval between successive pulse-generating operations.

6. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric current supply, load devices connected to said transmission line and at each end thereof, a normally non-conducting electronic space discharge device associated with each of said load devices and having a series connection therewith and a connection to ground, means operatively connected to said electronic space discharge devices for rendering said space discharge devices conductive to discharge rapidly the energy stored in said transmission line section and thereby initiate pulse generation and means for isolating said transmission line section from its source of electrical energy during the pulse generation period.

7. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric current supply, load devices, each having an impedance equal to the characteristic impedance of the transmission line section, connected, in series, to said transmission line and at each end thereof, a normally non-conducting electronic space discharge device associated with each of said load devices and having a series connection therewith and a connection to ground. means operatively connected to said electronic space discharge devices for rendering said space discharge devices conductive, and independently of one another, to discharge rapidly the energy stored in said transmission line section and thereby initiate pulse generation and means for isolating said transmission line section from its source of electrical energy during the pulse generation period.

8. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a'source oi electric current supply, load devices connected to said transmission line and at each end thereof, a. normally non-conducting electronic space discharge device associated with each of said load devices and having a series connection therewith and a connection to ground, means operatively connected to said electronic space discharge devices for rendering said space discharge devices conductive, and independently of one an,- other, to discharge rapidly the energy stored in said transmission line section and thereby initiate pulse generation and means for isolating said transmission line section from its source of electrical energy during the pulse generation periatrapar characteristic oi the transmission line section in a predetermned ratio between said load devices.

9. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission l line section having a connection to a source of electric current supply, load devices connected to said transmission line and -at each end thereof, a

normally non-conducting electronic space dis charge ldevice aociated with each of saidload devices and having a series connection therewith and a.v connection to ground, means operatively connected to said electronic lspace discharge devices for rendering said space discharge devices conductive, and independently of one another, to discharge rapidly the energy stored insaid transmission line section and thereby initiate pulse generation and means for isolating said transmission line section from its source or electrical energy during the pulse generation period. y

said means for rendering said space discharge devices conductive comprisingfmeans to establish the length of .the time interval between successive pulse-generating operations.

io. in a puise generating circuit, an eieccricai transmission line lsection, wherein electrical energy is adapted to be stored, said transmission -iine section having a connection to a source of electric current supply, load devices, each having an impedance equal to the characteristic imsedance or the transmission line section, connested, in series. to said transmission line and at each end thereof. a normally non-conducting electronic space discharge device associated with each of said load devices and having a series connection therewith and a connection' to ground, means operatively connected to said electronic space discharge devices for rendering said space discharge devices conductive, and independently one of another, to discharge rapidly lthe energy stored in said transmission line section and thereby initiate pulse generation and means for isolating said transmission line section from its source of electrical energy during the pulse generation period, said means for rendering said space dischargedevices conductive comprising means operative to effect division of the maximum pulse time width characteristic of the transmission line section in a predetermined ratio between said load devices, andcomprising means to establish the length of the time interval between successive pulse generatingoperations, the amplitude of the output pulse appearing at the load devices and the electrical energy drain of the transmission line section remaining substantially constant for all divisions of the output pulse time width.

11. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric current supply, load devices, each having an impedance equal to the characteristic impedance of the transmission line section, connected in series to said transmission line and at each end thereof, a normally non-conducting electronic space discharge device associated with each of said load devices and having a series connection therewith and a connection to ground, means operatively connected to said electronic space discharge devices for rendering said space discharge devices conductive, and independently lof one another, to discharge rapidly the energy 20 stored' in said thereby initiate pulse generation and means for isolating said vtransmission line section from its source of electrical energy during the pulse genv eration period.'said means. for rendering said electronic space discharge devices conductive including means operable to vary the time rela- ,f

lvices having an impedance equal to the characteristic impedance of the transmission line section, a normally non-conducting electronic space discharge device'associated with each of said load devices and having a series connection therewith and a connection to ground, means operatively connected tosaid electronic space discharge devices to provide pairs of triggering electrical pulses for rendering said space discharge devices conductive, and independently of one another, to discharge rapidly the energy stored in said transmission line section and thereby initiate pulse generation and means for isolating said transmission line section from its source of electrical energy during the pulse generation period, said means for rendering said electronic space discharge devices conductive comprising a plurality` of a normally non-conducting electronic space discharge device, one connected to each of said first mentioned discharge devices and adapted when lthey become conductive to trigger said first mentioned discharge devices into conduction, and means to provide bias voltage upon the control grids of said second mentioned discharge devices, said bias providing means including means to vary the bias provided upon at least one of said control grids of said second mentioned discharge devices.

13. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric current supply, a load device provided at each end of said transmission line section and connected in series thereto, each of said load devices having an impedance equal tothe characteristic impedance of the transmission line section, a normally non-conducting electronic space discharge device associated with each of said load devices and having a series connection therewith and a yconnection to Iground, means operatively connected to said electronic space discharge devices to provide" pairs of triggering electrical pulses for rendering said space discharge devices conductive, -and independently of one another, to discharge rapidly the energy stored in said transmission line section and thereby initiate pulse generation and means for isolating said transmission line section from its source of electrical energy during the pulse generation period, said means for rendering said electronic space discharge devices conductive comprising a plurality of a normally non-conducting electronic space discharge device, one connected to each of said iirst mentioned discharge devices and adapted when they become transmission line section and conductive to trigger said ilrst mentioned discharge devices into conduction, and means to provide bias voltage upon the control grids of said second mentioned discharge devices, said bias providing means including means to vary th bias provided upon the control grid of one of said second mentioned discharge devices and to provide a fixed bias voltage to the control grid of the other of said discharge devices, and means connected to said control grids to initiate periodically the iiow of current therethrough.

14. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric current supply, a pair of load devices connected in series to said transmission line, one at each end thereof, one of said load devices havlng an impedance equal to the characteristic impedance of the transmission line section, and the other of said load devices being subject to a variation of impedance with relation to the characteristic impedance of said transmission line section, a normally non-conducting electronic space discharge device associated with each of said load devices and having a series connection therewith and a -connection to ground, means operatively connected to said electronic space discharge devices for rendering said spa-ce discharge devices conductive, and independently of one another. to thereby initiate pulse generation and means for isolating said transmission line section from its source of' electrical energy during the pulse generation period.

15. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric current supply, a pair of load devices connected in series to said transmission line, one at each end thereof, one of said load devices having an impedance lower than the characteristic impedance of the transmission line section, and the other of said load devices being subject to a variation of impedance with relation to the characteristic impedance of said transmission line section, a normally non-conducting electronic space discharge device associated with each oi' said load devices and having a series connection therewith, and a connection to ground, means operatively connected to said electronic space discharge devices for independently rendering said space discharge devices conductive, and independently of one another, to discharge rapidly the energy stored in said transmission line section and thereby initiate pulse generation and means for isolating said transmission line Y 22 transmission line section and thereby eifect pulse generation.

1'7. In a pulse generating circuit, ain electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric current supply, loa-d devices connected to said transmission line and at each end thereof and means for intermittently electrically interconnecting sai-d load devices with said transmis- .sion line section comprising, two normally nongeneration, said means for yrendering said 'elecsection from its source of electrical energy during the pulse generation period.

16. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric current supply, load devices connected to said transmission line and at each end thereof and means for intermittently electrically interconnecting said load devices with said transmission line section comprising, two normally nonconducting electronic space discharge devices associated with each of said load devices and vhaving a series connection therewith and a connection to ground, and means operatively connected to said electronic space discharge devices for rendering, in pairs, saidA space discharge devices.

conductive alternately to store rapidly and to discharge rapidly the said energy stored in said tronic space discharge devices conductive comprising means operative on. said pairs of space discharge devices to render each member of a pair conductive independently of one another during a pulse generating operation.

` 18. In a p ulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric current supply, load devices connected to said transmission line and at each end thereof and means for intermittently 'electrically interconnecting said load devices with said transmission line section comprising, two normally nonconducting electronic space discharge devices associated with each of said load devi-ces and having a series connection therewith and a connection to ground, means operatively connected 'to said electronic space discharge devices .for rendering said space discharge devices conductive and in pairs comprised of one space discharge device at each end of said transmission line, one pair of which operates to rapidly charge the transmission line Vwith electrical energy and the other pair operates to rapidly discharge said stored energy, with pulse formation occurring during both the charging and the discharging of said transmission line.

19. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a Source of electric current supply, load devices connected to said transmission line and at each end thereof and means for intermittently electrically interconnecting said load devices with said transmission line section comprising, two normally nonconducting electronic space discharge devices associated with each of said load devices and having a series connection therewith and a' connection to ground, means operatively connected to said electronic space discharge devices for rendering said space discharge devices conductive and in pairs comprised of one space discharge device at each end of said transmission line, one pair of which operates to rapidly charge the transmission line with electrical energy while simultaneously forming pulses at said load devices. and the other pair operates to discharge said stored energy to form pulses.

,20. In a pulse generating circuit, an electrical transmission line section, wherein electrical energy is adapted to be stored, said transmission connecting said load devices with said transmissionline section comprising, a normally nonconducting electronic space discharge device associated with each oi' said load devices and having a series connection therewith and a connec tion to ground, and means operatively connected to said electronic space discharge devices for independently renderingl said space discharge de-v vices conductive to rapidly store energy in said transmission line section while simultaneously forming pulses at said load devices.

21.-In a pulse generating circuit. an electrical transmission v line section, wherein electrical energy is adapted to be stored, said transmission line section having a connection to a source of electric crrent supply, load devices connected to said transmission line and at each end thereof, a normally non-conducting electronic space discharge device associated with each of said load devices and having a series connection therewith and a connection to ground, means operatively I connected to said electronic space discharge de ille of this patent:

'l vices for independently rendering said space discharge devices conductive to' rapidly store env REFERENCES CITED The following references are oi record in the UNITED STATES PATENTS Number Name Date 2,405,069 yTonks Feb. 23, 1942 2,408,824` Varela Oct. 8, 1946 2,409,897 Rade Oct. 22, 1946 2,411,140 Lindenblad Nov. 12, 1946 2,420,309 Goodall May 13, 1947 2,429,471 Lord Oct. 21, 1947 2,446,838 Lawrence Apr. 10, 1948 2,458,574 Dow Jan. 11, 1949 2,470,550- Evans May 17, 1949 

